Where am I losing my top end?

[leemozoid]

For two years now I can't top 120 mph in the quarter. My tuner and I have been working one the systems and tune. Throughout this time the heat exchanger has been a fundamental issue along with the intermittent failures of the methanol injection. The first trip to the track this year was a dismal failure. My heat exchanger expansion tank split a seam due to backpressure from a collapsed brick. I replaced the collapsed brick with a reinforced unit, had the expansion tank repaired and the IAT2s now do not exceed 130F. The methanol system seems to work great on the street under light to WOT pulls but the usage at the track is way off even though the IAT2s are good. Bottom line, something is retarding timing or applying torque control to limit my mph in the quarter to 118-120 while on a 40 roll I can pull into the 140s and still have more.

Help! What do we need to look at to fix the track tune? Even the 1/4 sims on the dyno say 11.2/125 mph.

[Vegas Bound]

We have very similar builds. You should be in low 10s at the very least with the air in that area. I hate to say this but you might want to have another shop/tuner look at your build. A fresh set of eyes might see something that is currently being missed.

[leemozoid]

Originally Posted by Vegas Bound

We have very similar builds. You should be in low 10s at the very least with the air in that area. I hate to say this but you might want to have another shop/tuner look at your build. A fresh set of eyes might see something that is currently being missed.

I'll never see 10s with my heavy assed convertible. I'll be happy with low 11s. My tuner and I have about the same hp. I'm about 1000 lbs heavier than his C7 so I figure I should be about one second slower than him. Currently he's running right at 10 flat. We just need to find what in the tune is holding me back on my mph. I know what I need to do on my part to improve my starts and 60' times.

[GODZL1A]

Do you have any data logs?

[ZMEnow]

Originally Posted by Vegas Bound

We have very similar builds. You should be in low 10s at the very least with the air in that area. I hate to say this but you might want to have another shop/tuner look at your build. A fresh set of eyes might see something that is currently being missed.

No Doubt, I see 124 with Teds mail tune on the 125 package.

[RobZL1]

Post up a tune and log. I'd be glad to take a look. With that much mph drop, it should be fairly easy to spot.

[leemozoid]

Originally Posted by GODZL1A

Do you have any data logs?

No. We are going to do that the next trip to the track.

[RobZL1]

Other data points to consider from MotorTrend, testing a stock 2014 convertible back in the day. It drops a little compared to the coupe, but 118-120 mph is almost stock for a 'vert:

At the dragstrip, the 4405-pound Camaro ZL1 convertible automatic hit 60 mph in 4.1 seconds and finished the quarter mile in 12.5 seconds at 114.3 mph. In comparison, the 354-pound-lighter ZL1 coupe with a six-speed manual sprinted to 60 mph in 3.8 seconds and finished the quarter mile in 12.1 seconds at 117.4 mph. With a 60-mph stopping distance of 106 feet, the ZL1 convertible stopped 2 feet shorter than the coupe. Thanks to GM's Magnetic Ride Control suspension, the ZL1 convertible posted 1.01 g around the skidpad and lapped the figure eight in 24.1 seconds at 0.85 g average, putting it right on top of the coupe's handling numbers (1.02 g and 23.9 seconds at 0.83 g).

[Tajefe Couple]

Not a ZL1 just NA, but having the same issue always trapping right at 118 mph no matter my times ranging on average from 11.4-11.9. My build should be capable of high 10's or low 11's at the least. Be interesting to see if you get it solved.
Rob if you would look at a couple of logs I'd be happy to post them?

[leemozoid]

Originally Posted by Tajefe Couple

Not a ZL1 just NA, but having the same issue always trapping right at 118 mph no matter my times ranging on average from 11.4-11.9. My build should be capable of high 10's or low 11's at the least. Be interesting to see if you get it solved.
Rob if you would look at a couple of logs I'd be happy to post them?

Thanks for posting. Sorry to hear you're experiencing the same frustrations I am. Hopefully once we can get some logs posted we can start to get some answers to why we're underperforming.

[Little Walter]

How much timing is in the car at your higher RPM range

[JANNETTYRACING]

Originally Posted by leemozoid

For two years now I can't top 120 mph in the quarter. My tuner and I have been working one the systems and tune. Throughout this time the heat exchanger has been a fundamental issue along with the intermittent failures of the methanol injection. The first trip to the track this year was a dismal failure. My heat exchanger expansion tank split a seam due to backpressure from a collapsed brick. I replaced the collapsed brick with a reinforced unit, had the expansion tank repaired and the IAT2s now do not exceed 130F. The methanol system seems to work great on the street under light to WOT pulls but the usage at the track is way off even though the IAT2s are good. Bottom line, something is retarding timing or applying torque control to limit my mph in the quarter to 118-120 while on a 40 roll I can pull into the 140s and still have more.

Help! What do we need to look at to fix the track tune? Even the 1/4 sims on the dyno say 11.2/125 mph.

Lots of mods and poor performance.

Stock 13 ZL-1 auto with simple JRE 125 RWHP on 93 octane, no meth, no brick, no tank, no heat exchanger, no converter, no cam, stock upper 18% lower 12 psi boost, 11.0 125 in 89 degree humid weather on drag radials.



With all your mods you should be in the 9s 135+

Be glad to help you get it sorted out but expect to make changes to the combo and tuning.

Ted

[leemozoid]

Originally Posted by JANNETTYRACING

Lots of mods and poor performance.

Stock 13 ZL-1 auto with simple JRE 125 RWHP on 93 octane, no meth, no brick, no tank, no heat exchanger, no converter, no cam, stock upper 18% lower 12 psi boost, 11.0 125 in 89 degree humid weather on drag radials.



With all your mods you should be in the 9s 135+

Be glad to help you get it sorted out but expect to make changes to the combo and tuning.

Ted

I understand the tune is in major need of overhaul. What combo changes should I expect to make?

[JANNETTYRACING]

Originally Posted by leemozoid

I understand the tune is in major need of overhaul. What combo changes should I expect to make?

Feel free to call to discuss. 203-753-7223